I've used craigslist with dogs I've fostered in the past. most responses actually came from craigslist(well ones that were real people anyway). I couldn't post a pic on petfinder bc i'm not a rescue group.
anyway, it's the same with any other place. You really have to screen the people who call or email you. We all look on craigslist and petfinder, and I'm sure everyone on here has seen a dog on craigslist and said "OH, I know would love LOVE this dog!" and passed the information on. I think it's a great way to get your dogs out there, you just have to be careful who you choose to adopt to.